Jenny Watson, EOC chair, argued that the present system, which requires individual employees to enforce their rights by bringing tribunal claims, is not working and the tribunal system cannot cope with the volume of claims currently being brought.

However, Bronwyn McKenna, Unison director of organising and membership, said: “Women have legal rights under EU and UK law that must be respected and some employers will use a moratorium cynically to stave off claims indefinitely to stop progress to pay equity.

“Equal pay claims already involve going back over several years of a woman’s work history and evidence will go stale if claims are put on hold. The answer must surely be to shorten the length of time it takes for these claims to go through the courts.”

GMB national secretary Brian Strutton said: “Employers have a legal duty to implement equal pay for all women and they should just get on with it.

“The principle of equal pay for equal work is one of the key anti-discrimination provisions of EU law. It is a fundamental principle of EU law that individuals must be given an effective remedy for their rights which derive from European law,” he said.

“It is likely that the European Court of Justice would regard a moratorium on claims as denying individuals an effective remedy, regardless of the fact that the underlying aim of the policy would be to promote equality.”